Racket stringing machine



Feb. 7, 1967 w. J. HARTMAN 3,302,959

RACKET STRI NG ING MACHI NE Filed Dec. '7, 1965 38 26 44 24 S 60 64 56 3O 2/ w) WESLEY J. HARTMAN mwmm BUG/(HORN, BLO/FE, KL/IROU/ST 8 SPAR/(MAN ATTORNEYS United States Patent 3,302,950 RACKET STRHNGING MACHINE Wesley J. Hartman, 1893 SW. Orchid, Portland, Oreg. 97219 Filed Dec. 7, 1965, Ser. No. 512,050 3 Claims. (Cl. 273-73) This invention relates to a device that is capable of stringing tennis, badminton, squash and similar rackets.

Racket stringing machines are well known to the art. In general they comprise a frame for supporting the racket and a means for applying tension to the string. The racket-supporting frame usually has two movable jaws which can be moved toward and away from each other so that the frame of the racket to be strung can be held along its longitudinal axis, thereby to provide a rigid support for the racket during the stringing process.

A variety of devices have been proposed for applying tension to the strings. Many of these, however are unduly complicated and hence, ineflicient to operate. Others due to their construction make it impossible to repair a racket in which, for example, only a single string is broken. Still others have a tendency to injure the string during the stringing process, or are so constructed that they can be severely damaged themselves should the string suddenly snap while under tension.

Accordingly, it is an object of the present invention to provide an eflicient and economical racket stringing machine thet will enable any person to string tennis, badminton, squash and like rackets easily and quickly after a minimum period of instruction.

A further object of the present invention is to provide such a racket stringing machine that is capable of ready adjustment, thereby to be able to assist in the replacement of even a single broken string.

It is a further object of the present invention to provide such a racket stringing machine that will not injure the string during the stringing process.

It is a still further object of the present invention to provide such a racket stringing machine that has means to prevent injury to itself should a string suddenly and unexpectedly break during the stringing process.

These and other objects and advantages are achieved by combining with the usual racket supporting frame a horizontally-movable string tensioning device that can be positioned sufiiciently close to the racket supporting frame to enable tension to be applied to even a short length of broken string, thereby to assist in the replacement thereof. The tensioning device comprises a drum having a friction producing facing around which the string can be wound for the usual stringing operations. To enable short lengths of string to be grasped, the drum is provided with a plurality of pins which are threaded radially into the periphery thereof so that their heads extend above the facing. These heads are enlarged and smooth on their exterior so that a length of string can be wound around the necks thereof without injuring the string when such length is too short to be completely wound around the drum. An elongated lever and clutch mechanism are provided which are adapted to rotate the drum in one direction only, thereby to apply the necessary tension to the string. Finally, stop means are provided on the tensioning device and positioned so that should the string break suddenly or unexpectedly, the lever with its counterweights would be stopped before it can injure the machine.

The invention will be better understood by reference to the following specification and to the drawings which form a part thereof, in which:

FIG. 1 is a side elevational view of the racket stringing machine of the present invention;

FIG. 2 is a cross-sectional view taken on line 2-2 of FIG. 1; and

FIG. 3 is a sectional view taken on line 3-3 of FIG. 2.

The machine shown in the drawings comprises essentially a frame in which the racket is held rigidly during the stringing operation, a means for applying tension to the strings, and clamps for maintaining the strings under tension as the stringing progresses. Referring to FIG. 1, the machine includes a tubular standard or post 10 rising from a floor-anchored base plate 12, the upper end of the post 10 supporting a racket frame holding structure designated in general by the reference numeral 14. (It is to be understood, of course, that although a floormounted pedestal or post 10 is shown in the drawings and described herein, that other mountings could be used. For example, the base member 10 could be made shorter if it were desired to mount the apparatus on a table top.) An elongated plate 16 is pivotally supported adjacent one end as at 18 for rotation in a horizontal plane. A block 20 rigid with the free-swinging end of the plate 16 rises from said plate and carries an arm 22 provided at its free end with gripping jaws 24 for the support of one end of the looped frame portion 26 of a racket 30. A bar 32 is slideably connected with the block 20 and is held in adjustable position by a set screw 34, the other end of the bar 32 having an arm 36 rising therefrom that carries gripping jaws 38 for the support of the opposite side of the looped frame portion 26 of the racket 30. A horizontal stub shaft 40 projects laterally from the bar 32 and has mounted thereon one end of an elongated rod 42 extending parallel with the bar 32, the rod 42 adjustably supporting a string clamp 44, the clamp 44 being mounted on the rod 42 as shown in FIG. 1. The other end of the rod 42 is supported by a stub shaft 46 projecting laterally from the base of the arm 36. The clamp 44 is adapted to maintain the longitudinally extending strings under tension. Suitably mounted clamps (not shown) for maintaining the transverse strings under tension are also appropriately mounted on the bar 32.

A string tensioning device 48 is slideably mounted on a horizontal support 50 attached to the post 10 below the elongated plate 16. The tensioning device 48 includes an upstanding arm 52 having a base portion 53 held in adjustably sliding position on the horizontal support 50' by a releasable set screw 54. The arm 52 is inclined upwardly from the horizontal support 50 towards the pivotal 'axis 18 of the racket-supporting frame 14. Since the base portion 53 is slideably adjustable with respect to the horizontal support 50, the tensioning device 48 can be brought as close to the racket-supporting frame 14 as desired, thereby to enable tension to be applied to even a very short length of string.

At the top of the arm 52 is a fixed head 58, to which a drum 56 is rotata-bly attached by a retaining bolt 60 threadedly received into the head 58. (See FIG. 2.) The drum 56 has a friction producing facing 62 wound around it, such as a facing of rubber sheeting, and where sufficient lengths of racket string S are available, such are merely wound around the drum 56 one or more turns and overlapped, the facing 62 .providing the necessary holding friction. It should be noted that the top of the drum 56 is tangent to the center plane of the racket 30 when said racket is supported in the frame 14, thereby to assist in maintaining an even pull on the string S.

To enable short lengths of string to be grasped as would occur when a single broken string is to be replaced or when the stringing operation for a given racket is near completion, the drum 56 is provided with a plurality of pins 64 threaded radially into its periphery. (See FIGS. 2 and 3.) Each of the pins 64 has an enlarged ex-teriorly smooth head 66 extending above the facing 62. By this means even a very short length of string can be securely gripped when the tensioning device 48 is moved on the bar 50 close to the racket supporting frame 14, the string being wound around the neck of the pin 64 and kept from slipping off by the enlarged head 66. It should be noted that the pins 64 also assist in retaining the string S on the drum 56 when longer lengths of string are available and the string is merely wound around the drum. In this situation the string as it extends from the racket 30 is wrapped around the drum 56, with the end of the string coming from the racket placed over the loose end to keep the latter from slipping through as tension is applied, the drum 56 being positioned initially so that a pin 64 can retain the string crossed-over in the manner described.

Each of the pins 64 has an internal socket 68 (see FIG. 2) formed in its head 66 to accommodate a wrench for threading the pin into the drum 56. Since the pins 64 are thus entirely smooth on their exterior, the tensioning device of the present invention cannot injure the string during the stringing process.

A graduated elongated lever 70 having a hub 72 is pivoted about the retaining bolt 60 and is thus concentric with the drum 56. The hub 72 has a head 74 around which a clutch spring 76 is wound, one end 78 of the spring 76 being fixedly received into the drum 56. (See FIG. 2.) By this means rotation of the lever 70 in a clockwise direction as viewed in FIG. 1 causes the clutch spring 76 to grip the head 74, thereby to impart clockwise rotation to the drum 56 and tension to the string S. Rotation of the lever 70 in the counterclockwise direction as viewed in FIG. 1 causes the clutch spring 76 to release its grip on the head 74 and slip with respect thereto, thereby to permit the head 74 to rotate with respect to the drum 56. The lever 70 is provided with a sliding set of counterweights 80, 82 which can be fixed to the lever 70 by means of a screw 84. The inner counterweight 82 is utilized in the stringing of the lighter weight rackets. Both the counterweights 80 and 82 are used in the stringing of the heavier rackets, as will be obvious to those skilled in the art.

A stop 86 made of soft rubber is aifixed to the arm 52 on one side, as shown in FIG. 1. (By rubber is meant any natural or synthetic elastomeric material having rubber-like properties.) When the lever 70 is released, it swings downwardly, rotating the drum 56 to which the string S is attached either by bein wound around the facing 62 or by being wound around one of the pins 64. The desired tension is obtained by the selective adjustment of the counterweights 80, 82 along the graduated lever 70. or unexpectedly break, however, the rotation of the lever 70 will be arrested by contact with the stop 86, thereby to prevent damage to the machine.

The racket stringing machine of the present invention is suitable for the stringing of tennis, badminton and squash rackets and accomplishes all of the objects and advantages above set forth. It has been described with reference to a certain particular preferred embodiment, although it is to be understood that the specific details shown are merely illustrative and that the invention may be carried out in other ways without departing from the true spirit and scope of the following appended claims.

I claim:

1. In a machine for stringing rackets, the combination of a base member;

Should the string S suddenly a racket supporting frame pivotally mounted on said base member and adapted to support a racket with its center in a predetermined plane;

a horizontal support attached to and extending from said base member below said racket supporting frame; and

a string tensioning device slidea'bly mounted on said horizontal support, said tensioning device comprising an upstanding arm including a base portion having releasable means for clamping said base portion at various desired positions on said horizontal support,

said arm being inclined upwardly from said horizontal support towards the pivotal axis of said racket supporting frame,

a drum rotatably mounted at the top of said upstanding arm, the top of said drum being tangent to said center plane of said racket when supported in said racket supporting frame,

a friction producing facing on said drum,

a plurality of pins threaded radially into the periphery of said drum, each of said pins having an enlarged exteriorly smooth head extending above said facing,

clutch means mounted interiorly of said drum,

an elongated lever pivoted concentrically with said drum and attached to said clutch means, said clutch means being adapted to rotate said drum in the direction which will apply tension to racket string attached to said drum upon rotation of said lever in said direction and being adapted to slip within said drum upon rotation of said lever in the opposite direction,

at least one counter weight slideable along said lever,

means for securing said counterweight in various adjusted positions on said lever, and

stop means attached to said upstanding arm on one side thereof and adapted to limit the amount of rotation of said elongated lever in the tension applying direction.

2. The combination of claim 1, in which each of said pins has an internal socket formed in its head, said socket being adapted to accommodate a wrench for threading said pin into said drum.

3. The combination of claim 1, in which said stop means comprises an elastomeric stop.

References Cited by the Examiner UNITED STATES PATENTS 2,015,238 9/1935 Saladino 273-73 2,188,250 1/1940 Serrano 273-7 FOREIGN PATENTS 69,974 9/ 1949 Denmark.

References Cited by the Applicant UNITED STATES PATENTS 2,014,989 9/1935 Sieff. 2,246,109 6/ 1941 Serrano. 2,268,276 12/1941 Caro et al. 2,389,609 11/1945 Caro et al. 2,971,760 2/1961 Boykin et al.

WILLIAM FELDMAN, Primary Examiner.

MII TON S. MEHR, Examiner. 

1. IN A MACHINE FOR STRINGING RACKETS, THE COMBINATION OF A BASE MEMBER; A RATCHET SUPPORTING FRAME PIVOTALLY MOUNTED ON SAID BASE MEMBER AND ADAPTED TO SUPPORT A RACKET WITH ITS CENTER IN A PREDETERMINED PLANE; A HORIZONTAL SUPPORT ATTACHED TO AND EXTENDING FROM SAID BASE MEMBER BELOW SAID RACKET SUPPORTING FRAME; AND A STRING TENSIONING DEVICE SLIDEABLY MOUNTED ON SAID HORIZONTAL SUPPORT, SAID TENSIONING DEVICE COMPRISING AN UPSTANDING ARM INCLUDING A BASE PORTION HAVING RELEASABLE MEANS FOR CLAMPING SAID BASE PORTION AT VARIOUS DESIRED POSITIONS ON SAID HORIZONTAL SUPPORT, SAID ARM BEING INCLINED UPWARDLY FROM SAID HORIZONTAL SUPPORT TOWARDS THE PIVOTAL AXIS OF SAID RACKET SUPPORTING FRAME. A DRUM ROTATABLY MOUNTED AT THE TOP OF SAID UPSTANDING ARM, THE TOP OF SAID DRUM BEING TANGENT TO SAID CENTER PLANE OF SAID RACKET WHEN SUPPORTED IN SAID RACKET SUPPORTING FRAME, A FRICTION PRODUCING FACING ON SAID DRUM, A PLURALITY OF PINS THREADED RADIALLY INTO THE PERIPHERY OF SAID DRUM, EACH OF SAID PINS HAVING AN ENLARGED EXTERIORLY SMOOTH HEAD EXTENDING ABOVE SAID FACING, CLUTCH MEANS MOUNTED INTERIORLY OF SAID DRUM, AN ELONGATED LEVER PIVOTED CONCENTRAICALLY WITH SAID DRUM AND ATTACHED TO SAID CLUTCH MEANS, SAID CLUTCH MEANS BEING ADAPTED TO ROTATE SAID DRUM IN THE DIRECTION WHICH WILL APPLY TENSION TO RACKET STRING ATTACHED TO SAID DRUM UPON ROTATION OF SAID LEVER IN SAID DIRECTION AND BEING ADAPTED TO SLIP WITHIN SAID DRUM UPON ROTATION OF SAID LEVER IN THE OPPOSITE DIRECTION, AT LEAST ONE COUNTER WEIGHT SLIDEABLE ALONG SAID LEVER, MEANS FOR SECURING SAID COUNTERWEIGHT IN VARIOUS ADJUSTED POSITIONS ON SAID LEVER, AND STOP MEANS ATTACHED TO SAID UPSTANDING ARM ON ONE SIDE THEREOF AND ADAPTED TO LIMIT THE AMOUNT OF ROTATION OF SAID ELONGATED LEVER IN THE TENSION APPLYING DIRECTION. 